Dry-cell element and method of making the same



Patented Dec. 11, 1928,

LESLIE G. anunnss, or QLEJONIA, nEwcEitsEY.

DRY-CELL ELEMENT AND METHoD oF MAKING'THE slime.

No Drawing.

This invention relates to improvements in the method of preparing bobbins for use in dry cells, and more particularly for the galvanic cells of the bag type. In this type of cell, the active elements, consist of 'a-carbon rod, surrounded by'a mixture of manganese dioxide and finely groundcarbon or graphite, an electrolyte of ammonium chloride and zinc chloride, and a zinccup. The manganese dioxide and carbon are molded around the carbon rod and this, commonly termed the bobbin, is usually wrapped in gauze, cheese cloth, or like fabric, before insertion into the zinc cup containing the electrolyte. The purpose of this'cloth is to prevent the'bobbin from becoming disintegrated during the proccss'of insertion and the preparation of the cell, thereby cell;

The step of wrapping these bobbins is expensive, both because of the cost of cloth and also because of the 'cost of the labor of applying the cloth. I-Ieretofore, attempts have been made to avoid the necessityof wrapping the cells with cloth by making an insoluble coating or envelope upon the surface of the A bobbins.

These methods involved some process, such as dipping in one or more solutions, to replace that of wrapping with cloth. By

the present invention, I eliminate this wrapping process without the substitution of any other process and without replacing the cloth with an insoluble coating or envelope upon the surface of the bobbins. 1 I have found that when an alkali metal salt, such as calcium chloride, for example, and a sulphate or a carbonate are added in the dry state to the bobbin mix before molding, that after molding, these bobbins will be sufficiently hard to have sufiicient mechanical strength to allow the'handling that is necessary to complete the process ofassembling the battery. Although different sulphates may be used, I have'found aluminium sulphate to be preferable. place between these substances, added in this manner, is slow and allows a good workability of the mix during the process of molding the bobbins. I After a'period of two days, the bobbins are sufficiently hard and strong to allow their insertion into the cups without wrapping in cloth and withoutdanger of disintegration. Ithas been found that after causing-a short circuit within the a sulphate present. These materials arenot in- I jurious to the. battery. On the contrary, it has beenfound that.batteriesiproduced in this The chemical reaction which takes Application filed February 18, 1927. Serial No. 169,4lt3.'-'-- a the completion of. battery, these .bobbins remain rin a hard condition for nearly a 'day.

After the bobbins have been in contact with 1 A the electrolytefor a .periodgreater thanoneday, theybegin to softento suchan extent that the internalaresistance of the battery is even less than thatwof, batteries thathave been wrapped in acloth and made up without the addition of these substances. At thisstage, however, there is nodanger. of disintegration of the, bobbinssince they are held 1n place by the pasty condition ofthe electrolyte; The materials mentioned above may be used in varying amounts, but I prefer to, --use about one per centof aluminium sulphate alum may also'be. used satisfactorily) and one half of one per: centiof calcium chloride,

and prefer to have. an excess of aluminium manner have a voltage in excess of batteries made 111 the usual manner, and that the ,shelf l1fe 1s considerably increased. g

During the interaction ofitheabovementioned substances, calcium sulphateis produced and the hardening properties ofathe molded bobbin arelargely due to theformationsofthis compound; gCalciumsulphate,

when freshly precipitated, ..is somewhat s0 lu-,

ble in water and much more soluble in mineral bobbins become soft after coming in contact with the electrolyte, due to the dissolving of,

the substances which have previously caused the hardness.

This invention is not limited to the formation of calcium sulphate inthe bobbin, as other compounds, such'asbarium orother carbonates orcertain salts of silicic acid which have the propert 7 being formed an becoming soft by contact with hydrochloric acid, will produce similar results; 'Ihave'found that, for example, calof hardening soon after 'cium carbonate will, when produced within the bobbin, cause hardening of the bobbins r and Will, in turn, soften when in contact with gredients.

the electrolyte. Furthermore, aluminium sulphate alone will cause a slight hardening of the: bobbins.

I claim:

1. The method of producing bobbinswhich comprises adding substances, which will cause precipitation of a substance that will give hardness to the bobbin, to the bobbin ingredients and molding said substances with the bobbin ingredients.

2. The method of roducing bobbins which comprises adding su stances, one of which is 'asulphate, which will cause precipitation 01' substance that will give hardness tothe bobbin, to the bobbiningredients and molding said substances with the bobbin ingredients.

3. The method of producing bobbins which comprises adding substances, one of which is an alkali metal salt, which will cause precipitation ofa. substance that will give hardness to thebobbin, to the bobbin ingredients and molding said substances with the bobbin in- 4. The methodof producing bobbins which comprises adding a soluble alkaline earth metal salt and a soluble sulphate to the bobbin ingredients and molding said substances with the bobbin in redients.

5. The method 0 producing bobbins which comprises adding a calcium salt anda soluble sulphate to the bobbin ingredients and moldi'ng said substanceswwith the bobbin ingreclients. l i i 6. The method of producing bobbins which comprises adding a calcium chloride and'asoluble sulphate to the bobbin ingredients and molding said substances with the bobbin ingredients. 7

- 7 The method of producing bobbins which comprises adding a calcium chloride and an aluminium salt to the bobbin ingredients and dioxide and carbon mixed with ingredients that will react upon each other to harden the mixture in about two days and form a compound that is soluble indilute hydrochloric acid. V

10. A battery bobbin comprising manganese dioxide and carbon mixed with the reaction products of calcium chloride and alu-V n'iiniuni sulphate.

11. A battery bobbin comprising manganose dioxide and carbon mixed with the reaction products oi about one half of one per cent of calcium chloride and one per cent of.

aluminium sulphate.

12. The method of producing bobbins which comprises adding a. calciumchloride and aluminium sulphate to the bobbin ingredients andinolding said substances with the bobbin ingredients.

13. A battery bobbin comprising manganese dioxide and carbon mixed with a waterinsoluble hardeningsalt substantially uniformly distributed'in the depolarizing mix.

14;. A battery bobbin comprising manganese dioxide and carbon mixed with calcium sulphate.

LESLIE G. J ENNESS. 

